Chitosan-Polyphosphate Scaffold Loaded with Copper for Endodontic Regeneration: A Laboratory Study

ObjectiveRegenerative endodontics procedures show promise in treating immature teeth with necrotic pulp and apical periodontitis. This procedure involves the replacement of damaged and infected pulp tissue with viable tissue that restores the normal tooth structure and function. Antimicrobials are currently used to control the infection; however, they are cytotoxic to stem cells of the apical papilla (SCAP) and can lead to root canal calcification. Management of these teeth requires a scaffold that can control root canal infection, wick the blood into the canal, and support the viability and differentiation of SCAP while inhibiting intracanal calcification. This study aims to develop a composite scaffold made of polyphosphate, a calcium binding inorganic polymer shown to promote cell proliferation and tissue regeneration, chitosan, a natural antimicrobial polymer that supports stem cell viability and activity, and copper, a metal ion with bactericidal properties. MethodologyThe scaffold was prepared by adding copper (Cu) to chitosan solution, followed by polyphosphate. The resulting scaffold was then freeze-dried and analyzed for elemental composition, chemical structure, release of Cu, antibacterial properties, cytotoxicity, as well as differentiation and mineralization assays. Data were analysed by a two-way analysis of variance (ANOVA) followed by the Tukey post hoc test. ResultThis study demonstrates that, by combining polyphosphate and chitosan, we could fabricate a scaffold that inhibits bacterial growth by 40 % and supports the viability of fibroblast and SCAP. Adding copper to this scaffold further increased bacterial growth inhibition by up to 68% while preserving cell viability. The immunocytochemistry and Alizarin Red staining revealed that this scaffold also supports the odontogenic differentiation of these stem cells while inhibiting their mineralization potential. Furthermore, this scaffold can be fabricated as a 3D cone-shaped scaffold with a strong vertical wicking ability at a rate of 0.5 mm/s and excellent degradability, with 53 % of the scaffold degraded after 28 days. ConclusionsThis study shows that a copper-loaded chitosan-polyphosphate scaffold combines biocompatibility, antibacterial activity, wicking ability, and biodegradability and has great potential as an endodontic regenerative scaffold.